MINOR: spoe: Add SPOE filters in the exposed deprecated directives

It is the first deprecated directive exposed via the
'expose-deprecated-directives' global option. This way, it is possible to
silent the warning about the SPOE uses.

doc/configuration.txt

@@ -26625,7 +26625,8 @@ the Stream Processing Offload Protocol (SPOP).
 For all information about the SPOE configuration and the SPOP specification, see
 "doc/SPOE.txt".
 
-WARNING: The SPOE filter is now deprecated.
+WARNING: The SPOE filter is now deprecated. Use 'expose-deprecated-directives'
+         to silent warnings if you must use it.
 
 9.4. Cache
 ----------

reg-tests/spoe/wrong_init.vtc

@@ -12,6 +12,11 @@ varnishtest "SPOE bug: missing configuration file"
 feature ignore_unknown_macro
 
 haproxy h1 -conf-BAD {} {
+        global
+.if version_atleast(3.0-dev6)
+            expose-deprecated-directives
+.endif
+
 	defaults
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
         timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"

src/flt_spoe.c

@@ -4106,7 +4106,9 @@ parse_spoe_flt(char **args, int *cur_arg, struct proxy *px,
 	curpxopts2 = 0;
 
 
-	ha_warning("Proxy %s: SPOE filter is deprecated and will be removed in future version.\n", px->id);
+	if (!deprecated_directives_allowed)
+		ha_warning("Proxy %s: SPOE filter is deprecated and will be removed in future version. "
+			   "Use 'expose-deprecated-directives' in global section to silent this warning\n", px->id);
 
 	conf = calloc(1, sizeof(*conf));
 	if (conf == NULL) {